Vimala Venkatesh

Polymorphisms of TNF-enhancer and gene for FcγRIIa correlate with the severity of falciparum malaria in the ethnically diverse Indian population

BackgroundSusceptibility/resistance to Plasmodium falciparum malaria has been correlated with polymorphisms in more than 30 human genes with most association analyses having been carried out on patients from Africa and south-east Asia. The aim of this study was to examine the possible contribution of genetic variants in the TNF and FCGR2A genes in determining severity/resistance to P. falciparum malaria in Indian subjects.MethodsAllelic frequency distribution in populations across India was first determined by typing genetic variants of the TNF enhancer and the FCGR2A G/A SNP in 1871 individuals from 55 populations. Genotyping was carried out by DNA sequencing, single base extension (SNaPshot), and DNA mass array (Sequenom). Plasma TNF was determined by ELISA. Comparison of datasets was carried out by Kruskal-Wallis and Mann-Whitney tests. Haplotypes and LD plots were generated by PHASE and Haploview, respectively. Odds ratio (OR) for risk assessment was calculated using EpiInfo™ version 3.4.ResultsA novel single nucleotide polymorphism (SNP) at position -76 was identified in the TNF enhancer along with other reported variants. Five TNF enhancer SNPs and the FCGR2A R131H (G/A) SNP were analyzed for association with severity of P. falciparum malaria in a malaria-endemic and a non-endemic region of India in a case-control study with ethnically-matched controls enrolled from both regions. TNF -1031C and -863A alleles as well as homozygotes for the TNF enhancer haplotype CACGG (-1031T>C, -863C>A, -857C>T, -308G>A, -238G>A) correlated with enhanced plasma TNF levels in both patients and controls. Significantly higher TNF levels were observed in patients with severe malaria. Minor alleles of -1031 and -863 SNPs were associated with increased susceptibility to severe malaria. The high-affinity IgG2 binding FcγRIIa AA (131H) genotype was significantly associated with protection from disease manifestation, with stronger association observed in the malaria non-endemic region. These results represent the first genetic analysis of the two immune regulatory molecules in the context of P. falciparum severity/resistance in the Indian population.ConclusionAssociation of specific TNF and FCGR2A SNPs with cytokine levels and disease severity/resistance was indicated in patients from areas with differential disease endemicity. The data emphasizes the need for addressing the contribution of human genetic factors in malaria in the context of disease epidemiology and population genetic substructure within India.

Onychomycosis in central India: a clinicoetiologic correlation

Background  Onychomycosis is mainly caused by dermatophytes, but yeasts and nondermatophyte molds have also been implicated, giving rise to diverse clinical presentations. The etiological agents of the disease may show geographic variation. The aim of the present study was to isolate the causative pathogens and to determine the various clinical patterns of onychomycosis in central India.

CR1 levels and gene polymorphisms exhibit differential association with falciparum malaria in regions of varying disease endemicity.

Complement receptor 1 (CR1/CD35) levels on erythrocytes and related CR1 polymorphisms have been associated with response to falciparum malaria in populations inhabiting malaria-endemic regions. Differences in disease association profiles of its low expression alleles have been observed in populations from different regions of the world. We analyzed the influence of CR1 levels and associated SNPs on susceptibility/resistance to falciparum malaria in Indian populations. Two CR1 SNPs [exon 22 (A/G) and intron 27 (A/T)] define the low expression (L) CR1 allele in populations inhabiting a Plasmodium falciparum-endemic and a nonendemic region of India. Populations of the endemic region have very low red blood cell surface CR1 levels and higher frequencies of the exon 22 and intron 27 mutant L alleles. Whereas low CR1 levels correlated with susceptibility to severe malaria in the nonendemic region, high CR1 levels were associated with manifestation of disease in the endemic region. In addition, the exon 22 L allele was a risk factor for severe malaria in the nonendemic region. Absence of correlation between levels of tumor necrosis factor-alpha, interferon-gamma, and interleukin-6 with CR1 levels in patients with severe disease indicated that RBC CR1 levels in individuals are not the major determinants of pro-inflammatory cytokine release during infection. Our results are interpreted in the context of differences in the pathogenesis of severe malaria in the malaria-endemic and nonendemic region.

Variations in host genes encoding adhesion molecules and susceptibility to falciparum malaria in India

BackgroundHost adhesion molecules play a significant role in the pathogenesis of Plasmodium falciparum malaria and changes in their structure or levels in individuals can influence the outcome of infection. The aim of this study was to investigate the association of SNPs of three adhesion molecule genes, ICAM1, PECAM1 and CD36, with severity of falciparum malaria in a malaria-endemic and a non-endemic region of India.MethodsThe frequency distribution of seven selected SNPs of ICAM1, PECAM1 and CD36 was determined in 552 individuals drawn from 24 populations across India. SNP-disease association was analysed in a case-control study format. Genotyping of the population panel was performed by Sequenom mass spectroscopy and patient/control samples were genotyped by SNaPshot method. Haplotypes and linkage disequilibrium (LD) plots were generated using PHASE and Haploview, respectively. Odds-ratio (OR) for risk assessment was estimated using EpiInfo™ version 3.4.ResultsAssociation of the ICAM1 rs5498 (exon 6) G allele and the CD36 exon 1a A allele with increased risk of severe malaria was observed (severe versus control, OR = 1.91 and 2.66, P = 0.02 and 0.0012, respectively). The CD36 rs1334512 (-53) T allele as well as the TT genotype associated with protection from severe disease (severe versus control, TT versus GG, OR = 0.37, P = 0.004). Interestingly, a SNP of the PECAM1 gene (rs668, exon 3, C/G) with low minor allele frequency in populations of the endemic region compared to the non-endemic region exhibited differential association with disease in these regions; the G allele was a risk factor for malaria in the endemic region, but exhibited significant association with protection from disease in the non-endemic region.ConclusionThe data highlights the significance of variations in the ICAM1, PECAM1 and CD36 genes in the manifestation of falciparum malaria in India. The PECAM1 exon 3 SNP exhibits altered association with disease in the endemic and non-endemic region.

Distinct cytokine profiles define clinical immune response to falciparum malaria in regions of high or low disease transmission

The immune effector response to Plasmodium falciparum infection involves a finely-tuned interplay between different cell types and cytokines. However, the processes by which they mediate the development of clinical immunity, in areas of different endemicity, are poorly understood. We analyzed circulating levels of pro-inflammatory (TNF, IFN-γ, IL-12, IL-16) and anti-inflammatory (IL-4, IL-10, IL-13) cytokines in control and patient groups drawn from a P. falciparum-endemic and a non-endemic region of India. The endemic region control population exhibited a lower pro- to anti-inflammatory cytokine ratio, indicating a shift towards a high basal Th2 response. Levels of IL-10 contributed most towards the region-specific difference in basal cytokine response. IL-10 was also the strongest predictor of disease in the endemic region, while IL-12, along with IL-10 and IL-6, contributed most to disease outcome in the non-endemic region. A low, mean IFN-γ/IL-10 ratio was associated with disease severity in the endemic region (p < 0.0001). In contrast, a low mean IL-12/IL-10 ratio correlated with disease outcome in the non-endemic region (p < 0.0001). In the endemic region, IL-13 correlated negatively with IFN-γ in severe patients (Spearmans ρ: -0.49; p : 0.013), while in the non-endemic region, IL-13 correlated negatively with IL-6 in severe malaria patients (Spearmans ρ: -0.485; p : 0.001). In conclusion, levels of pro- and anti-inflammatory cytokines and the relative balance between the Th1 and Th2 response, illustrates how populations residing in areas of varying disease endemicity may respond to P. falciparum-induced immune challenge.

Ectopic fascioliasis in the dorsal spine: case report.

OBJECTIVE:Parasitic myelopathy is rare. We report ectopic infestation of the spine by Fasciola hepatica. CLINICAL PRESENTATION:A young woman presented with gradual onset paraplegia with bladder and bowel involvement. A magnetic resonance imaging scan showed an epidural mass lesion that was isotense on T1-weighted images and hyperintense on T2-weighted images, extending from T4–T7 vertebra with extradural cord compression. She was diagnosed with cord compression, possibly owing to tubercular epidural granulation tissue. INTERVENTION:During surgery, a mobile, flat, leaf-like, pink parasite was found in the epidural space. Morphological and histological indices confirmed the parasite as Fasciola hepatica. CONCLUSION:Ectopic spinal localization of Fasciola may occur during the transmigration path of the parasite through peritoneum or from the liver through portal venous system.

Deletion of the APOBEC3B gene strongly impacts susceptibility to falciparum malaria

APOBEC3B, a gene involved in innate response, exhibits insertion-deletion polymorphism across world populations. We observed the insertion allele to be nearly fixed in malaria endemic regions of sub-Saharan Africa as well as populations with high malaria incidence in the past. This prompted us to investigate the possible association of the polymorphism with falciparum malaria. We studied the distribution of APOBEC3B, in 25 diverse Indian populations comprising of 500 samples and 176 severe or non-severe Plasmodium falciparum patients and 174 ethnically-matched uninfected individuals from a P. falciparum endemic and a non-endemic region of India. The deletion frequencies ranged from 0% to 43% in the Indian populations. The frequency of the insertion allele strikingly correlated with the endemicity map of P. falciparum malaria in India. A strong association of the deletion allele with susceptibility to falciparum malaria in the endemic region (non-severe vs. control, Odds ratio=4.96, P value=9.5E(-06); severe vs. control, OR=4.36, P value=5.76E(-05)) was observed. Although the frequency of deletion allele was higher in the non-endemic region, there was a significant association of the homozygous deletion genotype with malaria (OR=3.17, 95% CI=1.10-10.32, P value=0.0177). Our study also presents a case for malaria as a positive selection force for the APOBEC3B insertion and suggests a major role for this gene in innate immunity against malaria.

Prevalence of gyrA and B gene mutations in fluoroquinolone-resistant and -sensitive clinical isolates of Mycobacterium tuberculosis and their relationship with MIC of ofloxacin.

The study was done to know the prevalent mutations of gyrA and gyrB genes, and their significance with drug resistance in clinical isolates of Mycobacterium tuberculosis. A total of 100 ofloxacin- (OFX) resistant and 100 OFX-sensitive isolates of M. tuberculosis were consecutively selected from routine Tuberculosis laboratory. Drug resistance pattern of these isolates was recorded. MIC of OFX was tested in all these isolates by absolute concentration method. Quinolone resistance determining region (QRDR) of gyrA and gyrB genes of 320 and 428 bp, respectively, were amplified and sequenced. Sequencing data were analyzed by BLAST on NCBI with reference strain H37Rv. Of 100 OFX-sensitive isolates, 30 were pansusceptible, 28 were monoresistant, 10 were polyresistant and 32 were multidrug resistant (MDR). Among 100 OFX-resistant isolates, 19 were OFX monoresistant, 16 were polyresistant and 65 were MDR. Mutations in gyrA and gyrB genes were observed in 79% and 5% of OFX-resistant isolates, respectively. Most prevalent mutation was found at codon 94 in QRDR of gyrA gene. Double mutations found in gyrA gene and in both gyrA and gyrB genes signifies higher levels of OFX resistance. In one isolate, a substitution at codon 592 (Pro592Ser) was found as a novel mutation outside the QRDR of gyrB gene. Our findings support previous studies that the OFX resistance to M. tuberculosis is associated with mutations in the QRDR of gyrA gene; however, the level of OFX resistance may not be predicted based on the mutation patterns in the gyrA gene.

Oropharyngeal candidiasis and Candida colonization in HIV positive patients in northern India.

INTRODUCTION Oropharyngeal candidiasis (OPC) is the most common opportunistic fungal infection reported in human immunodeficiency virus (HIV) positive patients worldwide. This prospective study was undertaken to investigate OPC and Candida colonization (CC) and their correlation with CD4+ cell counts and antiretroviral therapy (ART) in HIV-positive patients. METHODOLOGY In total, 190 HIV-positive patients were enrolled for study in three groups as follows: Group A, 90 patients without ART; Group B, 100 patients undergoing treatment with ART; and Group C, 75 HIV-negative control patients. All HIV patients underwent clinical examination and were subjected to CD4+ cell counts. Swabs were collected from the oral cavity of all individuals and plated on Sabourauds dextrose agar. Identification of Candida species was performed by conventional methods. RESULTS Candida species were isolated in 84/190 (44.2%) and 20/75 (26.6%) of the HIV-positive subjects and controls respectively (p<0.01). OPC was noted in 21/190 (11%) of the HIV-positive patients. Candida albicans was the most frequently isolated species. Patients with CD4+ cell counts ≤ 200 cells/mm3 were significantly (p<0.001) more frequently colonized (37/63; 58.7%) and infected (18/21; 85.7 %) with Candida species. Candida species was seen in patients with CC and OPC with CD4+cell counts between 201 and 500 (21/63; 33.4% vs 3/21; 14.3%) and > 500 cell/mm3 (5/63; 7.9% versus 0/21 0%) respectively. CONCLUSION OPC and Candida colonization occur more frequently in HIV-positive patients with CD4+ cell counts ≤ 200 cell/mm3. ART significantly reduces OPC. C. albicans is the most frequently isolated species in both OPC and colonization, suggesting endogenous infection.

Altered structural brain changes and neurocognitive performance in pediatric HIV

Pediatric HIV patients often suffer with neurodevelopmental delay and subsequently cognitive impairment. While tissue injury in cortical and subcortical regions in the brain of adult HIV patients has been well reported there is sparse knowledge about these changes in perinatally HIV infected pediatric patients. We analyzed cortical thickness, subcortical volume, structural connectivity, and neurocognitive functions in pediatric HIV patients and compared with those of pediatric healthy controls. With informed consent, 34 perinatally infected pediatric HIV patients and 32 age and gender matched pediatric healthy controls underwent neurocognitive assessment and brain magnetic resonance imaging (MRI) on a 3 T clinical scanner. Altered cortical thickness, subcortical volumes, and abnormal neuropsychological test scores were observed in pediatric HIV patients. The structural network connectivity analysis depicted lower connection strengths, lower clustering coefficients, and higher path length in pediatric HIV patients than healthy controls. The network betweenness and network hubs in cortico-limbic regions were distorted in pediatric HIV patients. The findings suggest that altered cortical and subcortical structures and regional brain connectivity in pediatric HIV patients may contribute to deficits in their neurocognitive functions. Further, longitudinal studies are required for better understanding of the effect of HIV pathogenesis on brain structural changes throughout the brain development process under standard ART treatment.